The invention relates to an injection moulding method for optional manufacturing of moulded parts with and without a breakthrough, in which
an injection-moulding tool is used, having a mould cavity delimited by at least one nozzle-side and at least one ejector-side mould platen and a mould core able to be at least partly positioned in the mould cavity, able to be moved relatively in relation to at least one of the mould platens, especially the nozzle-side mould platen in an advance and withdrawal direction, whereby said mould core is approached when moving in the advance direction by the respective other mould platen, especially the nozzle-side mould platen, and for a movement in the withdrawal direction, moves away from the latter,
to manufacture a moulded part with breakthrough the mould core is positioned in the mould cavity and to manufacture a moulded part without breakthrough the mould core is removed at least partly from the mould cavity.
In a method of the type described above there is the danger that the mould core, when it comes up against the inner side of the other, especially the nozzle-side mould platen, at least after a long period of operation or after a plurality of injection-moulding shots and accompanying closed positions of the two mould platens, will leave a permanent impression on the inner side of the other, especially nozzle-side mould platen. This impression is evident on the corresponding side of the moulded part, which especially cannot be tolerated when this side is the visible side of the moulded part and is intended to have an optically attractive design, is a high-gloss part for example.
The invention relates especially to an injection-moulding method for optional manufacturing of moulded parts with and without breakthrough. An injection moulding tool is used for such a process, which comprises at least one mould cavity delimited by one or more nozzle-side and one or more ejector-side mould platens and a mould core able to be positioned in the mould cavity. A nozzle-side mould platen, which can consist of a number of part platens, is especially a mould platen such as is held in a fixed position on an injection-moulding machine and via which, with the aid of an injection channel, a molten liquid plastic mass is injected into the mould cavity. The injection-moulding tool can naturally also have a number of such mould cavities. Compared to the preferably fixed, preferably nozzle-side mould platen, the ejector-side mould platen can expediently be embodied as a movable part. The mould core can expediently be attached to it, preferably detachably or to allow relative movement.
Expressed in general terms, at least one first mould platen is thus able to be moved relative to a second mould platen. The mould core in such cases can be assigned to the first and/or second mould platen or especially in a particularly suitable manner in the mould cavity embodied between the at least two mould platens and delimited by them, to allow movement into and out of the cavity.
To manufacture a moulded part with a breakthrough the mould core is positioned in the mould cavity, i.e. it occupies an area of the cavity corresponding to the subsequent breakthrough. To manufacture a moulded part without breakthrough the mould core is at least partly removed from the mould cavity. The mould core used in the injection-moulding process is also movable in an advance and withdrawal direction, preferably against the other, especially nozzle-side mould platen, whereby, for a movement in the advance direction it moves closer to the other, especially nozzle-side mould platen and for a movement in the withdrawal direction moves away from the latter.